2019 Volume 62 Issue 4 Pages 226-231
An 81-year-old woman was treated for ulcerative colitis at the Department of Gastroenterology of Kawanishi City Hospital. Because her HbA1c measured by standard-mode (SM)-high-performance liquid chromatography (HPLC) method (G8) showed a maximum value of 11.4 %, she was referred to our department for detailed examinations of high HbA1c levels. Since her randomly measured plasma glucose was 143 mg/dL and glycated albumin was 16.7 %, there was a discrepancy between these results and the HbA1c level. Based on the results of a 75-g oral glucose tolerance test, she was diagnosed with mild diabetes mellitus. All HbA1c levels measured with the SM-HPLC method (HA-8180), immunoassay, enzymatic assay and affinity assay were between 6.3 % and 6.5 %. The fraction of labile HbA1c (LA1c+) in HPLC (G8) was also quite high, at 4.2 % (reference range 1.7 %-2.7 %). Therefore, we suspected her of having variant hemoglobin and analyzed the globin gene. Consequently, we found a heterozygous mutation of the α2-globin chain and diagnosed her with Hb Prato (α2 31Arg→Ser). There are three case reports of Hb Prato, and this is the first case with HbA1c measurement. Hb Prato is a rare variant hemoglobin characterized by the HbA1c levels measured on HPLC differing depending on the model used, showing falsely high or true values.
